Increased secretions are a major source of morbidity in chronic sinusitis. Epithelial cells are responsible for much of the secretions of the upper airway, including both the electrolyte and water secreted by the surface epithelium and the mucous glycoproteins secreted by gland and goblet cells. The central hypothesis of this project is that abnormal epithelial cell function plays a major role in producing the abnormal secretions in this disease. Three specific aims will be addressed. Specific aim #1: In vivo nasal epithelial potential difference and, in patients who have had sinus surgery, ethmoidal sinus epithelial potential difference, will be measured. The responses to topical amiloride (to determine the contribution of sodium absorption to transepithelial potential), indomethacin (to determine the role of cyclooxygenase products and, indirectly, the contribution of chloride secretion), and isoproterenol (to determine whether cAMP-dependent chloride channels are intact) will be tested. Repeated measurements will be made during period of clinical quiescence and exacerbation of their sinusitis. Correlations of these results with in vitro ion transport studies using cultured epithelium (specific aim #2), as well as with the results of the measurement of cytokines and virus recovery in nasal and sinus lavage (Project #2) and the results of analysis of the genetic determinants of ion transport (Project #1) will be made. Specific aim #2: Ion transport will be measured in vitro using cultured monolayers of epithelial cells grown from resected ethmoidal sinus mucosal tissues. Sodium and chloride transport will be determined. Responses to tachykinins, bradykinin, and isoproterenol will be determined. The effects of in vitro infection of these cells with influenza, parainfluenza, and rhinovirus on ion transport, on responses to the above agonists, and on the ionic permselectivity of the paracellular pathway (measured using diffusing potentials) will be measured. Results of these in vitro studies will be compared with similar studies using epithelium cultured from normal sphenoidal sinus tissues obtained during transspenoidal hypophysectomy. Results will be correlated with the findings of Project #1. IL-6, IL-8, and GM-CSF content in the supernatants of these cultures (measured by ELISA), as well as expression of the corresponding genes (by Northern blot), will be measured and compared with the results of Project #2. Specific aim #3: To determine the extent to which chronic inflammation, by decreasing neutral endopeptidase activity, might increase tachykinin- stimulated mucous glycoprotein secretion, the secretory responses of resected sinus tissues to substance P in the presence and absence of a neutral endopeptidase inhibitor will be measured. This will be compared with similar experiments using normal sphenoidal sinus tissues. Neutral endopeptidase activity of tissue homogenates will also be measured fluorometrically. As symptomatic relief is a major goal of treatment of chronic sinusitis, a greater understanding of the pathophysiology of the major source of these symptoms, e.i., increased secretions, will allow the development of new therapeutic strategies in the management of this disease.